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Q112
(IAS/2008)
Science & Technology › Basic Science (Physics, Chemistry, Biology) › Basic chemical principles
Answer Verified
What are Rubies and Sapphires chemically known as?
Result
Your answer:
—
·
Correct:
B
Explanation
Rubies and sapphires are both gem-quality varieties of the mineral corundum, whose chemical composition is crystalline aluminium oxide, Al2O3 [1]. The red color of ruby arises from chromium (Cr3+) substituting for some aluminium in the corundum lattice, while other trace impurities produce the various colors seen in sapphires; but the host mineral in both cases remains Al2O3 [1]. The chemical formula Al2O3 is consistent with aluminium’s oxidation to form aluminium oxide (e.g., 4Al + 3O2 → 2Al2O3), confirming that aluminium oxide is the correct chemical identity for corundum-based gemstones [2]. Hence option 2 (Aluminium oxide) is correct.
Sources
- [1] https://www.gemstone.org/science-of-stones-ruby
- [2] Science , class X (NCERT 2025 ed.) > Chapter 3: Metals and Non-metals > Activity 3.9 > p. 41
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